Removal of well-fixed, cementless, acetabular components during revision arthroplasty remains a challenging problem. Further damage to host bone may limit options for reconstruction and compromise the long-term result of the revision operation. We report the results of 31 hips with well-fixed, cementless sockets which were removed using a new cup extraction system. In all hips the socket was removed without difficulty and with minimal further bone loss.

We have undertaken a prospective evaluation of health-related quality-of-life outcomes in 26 consecutive patients undergoing periacetabular osteotomy with a minimum follow-up of 24 months (24 to 42). The Western Ontario-Macmaster (WOMAC) and Short Form 36 (SF-36) outcome measures were evaluated preoperatively and at follow-up. Secondary outcome measures included retrospective assessment of sports activity and satisfaction with the procedure.

Follow-up data were available for 22 patients (85%). A significant improvement in the pain (p < 0.0001) and function (p < 0.0001) scales of the WOMAC and the SF-36 physical score (p < 0.0001) was seen. The mean sports activity score improved from 1.9 to 4.4, with a very high mean satisfaction rating of 89.7/100.

A significant improvement in both global and disease-specific health outcomes can be expected after this operation, with a high rate of satisfaction and improvement in sporting activities.

We have examined whether primary human muscle-derived cells can be used in ex vivo gene therapy to deliver BMP-2 and to produce bone in vivo. Two in vitro experiments and one in vivo experiment were used to determine the osteocompetence and BMP-2 secretion capacity of cells isolated from human skeletal muscle.

We isolated five different populations of primary muscle cells from human skeletal muscle in three patients. In the first in vitro experiment, production of alkaline phosphatase by the cells in response to stimulation by rhBMP-2 was measured and used as an indicator of cellular osteocompetence. In the second, secretion of BMP-2 was measured after the cell populations had been transduced by an adenovirus encoding for BMP-2. In the in vivo experiment, the cells were cotransduced with a retrovirus encoding for a nuclear localised β-galactosidase gene and an adenovirus encoding for BMP-2. The cotransduced cells were then injected into the hind limbs of severe combined immune-deficient (SCID) mice and analysed radiographically and histologically. The nuclear localised β-galactosidase gene allowed identification of the injected cells in histological specimens. In the first in vitro experiment, the five different cell populations all responded to in vitro stimulation of rhBMP-2 by producing higher levels of alkaline phosphatase when compared with non-stimulated cells. In the second, the five different cell populations were all successfully transduced by an adenovirus to express and secrete BMP-2. The cells secreted between 444 and 2551 ng of BMP-2 over three days. In the in vivo experiment, injection of the transduced cells into the hind-limb musculature of SCID mice resulted in the formation of ectopic bone at 1, 2, 3 and 4 weeks after injection. Retroviral labelling of the cell nuclei showed labelled human muscle-derived cells occupying locations of osteoblasts in the ectopic bone, further supporting their osteocompetence.

Cells from human skeletal muscle, because of their availability to orthopaedic surgeons, their osteocompetence, and their ability to express BMP-2 after genetic engineering, are an attractive cell population for use in BMP-2 gene therapy approaches.

We present a study of ten consecutive patients who underwent excision of thoracic or thoracolumbar hemivertebrae for either angular deformity in the coronal plane, or both coronal and sagittal deformity. Vertebral excision was carried out anteriorly alone in two patients. Seven patients had undergone previous posterior spinal fusion. Their mean age at surgery was 13.4 years (6 to 19). The mean follow-up was 78.5 months (20 to 180). The results were evaluated by radiological review of the preoperative, postoperative and most recent follow-up films.

The mean preoperative coronal curve was 78.2° (30 to 115) and was corrected to 33.9° (7 to 58) postoperatively, a mean correction of 59%. Preoperative coronal decompensation of 35 mm was improved to 11 mm postoperatively. Seven patients had significant coronal decompensation preoperatively, which was corrected to a physiological range postoperatively. There were no major complications and no neurological damage.

We have shown that resection of thoracic and thoracolumbar hemivertebrae can be performed safely, without undue risk of neurological compromise, in experienced hands.

The pathogenesis of aseptic loosening of total joint prostheses is not clearly understood. Two features are associated with loosened prostheses, namely, particulate debris and movement of the implant. While numerous studies have evaluated the cellular response to particulate biomaterials, few have investigated the influence of movement of the implant on the biological response to particles. Our aim was therefore to test the hypothesis that excessive mechanical stimulation of the periprosthetic tissues induces an inflammatory response and that the addition of particulate biomaterials intensifies this.

We allocated 66 adult Beagle dogs to four groups as follows: stable implants with (I) and without (II) particulate polymethylmethacrylate (PMMA) and moving implants with (III) and without (IV) particulate PMMA. They were then evaluated at 2, 4, 6, 12 and 24 weeks.

The stable implants were well tolerated and a thin, fibrous membrane of connective tissue was observed. There was evidence of positive staining in some cells for interleukin-6 (IL-6). Addition of particulate PMMA around the stable implants resulted in an increase in the fibroblastic response and positive staining for IL-6 and tumour necrosis factor-alpha (TNF-α). By contrast, movement of the implant resulted in an immediate inflammatory response characterised by large numbers of histiocytes and cytokine staining for IL-1ß, TNF-α and IL-6. Introduction of particulate PMMA aggravated this response. Animals with particulate PMMA and movement of the implant have an intense inflammatory response associated with accelerated bone loss.

Our results indicate that the initiation of the inflammatory response to biomaterial particles was much slower than that to gross mechanical instability. Furthermore, when there was both particulate debris and movement, there was an amplification of the adverse tissue response as evidenced by the presence of osteolysis and increases in the presence of inflammatory cells and their associated cytokines.

Caveolae, specialised regions of the cell membrane which have been detected in a wide range of mammalian cells, have not been described in bone cells. They are plasmalemmal invaginations, 50 to 100 nm in size, characterised by the presence of the structural protein, caveolin, which exists as three subtypes. Caveolin-1 and caveolin-2 are expressed in a wide range of cell types whereas caveolin-3 is thought to be a muscle-specific subtype. There is little information on the precise function of caveolae, but it has been proposed that they play an important role in signal transduction.

As the principal bone-producing cell, the osteoblast has been widely studied in an effort to understand the signalling pathways by which it responds to extracellular stimuli. Our aim in this study was to identify caveolae and their structural protein caveolin in normal human osteoblasts, and to determine which subtypes of caveolin were present. Confocal microscopy showed staining which was associated with the plasma membrane. Transmission electron microscopy revealed the presence of membrane invaginations of 50 to 100 nm, consistent with the appearance of caveolae. Finally, we isolated protein from these osteoblasts, and performed Western blotting using anti-caveolin primary antibodies. This revealed the presence of caveolin-1 and -2, while caveolin-3 was absent.

The identification of these structures and their associated protein may provide a significant contribution to our further understanding of signal transduction pathways in osteoblasts.

We studied the effect of the surface finish of the stem on the transfer of load in the proximal femur in a sheep model of cemented hip arthroplasty. Strain-gauge analysis and corresponding finite-element (FE) analysis were performed to assess the effect of friction and creep at the cement-stem interface.

No difference was seen between the matt and polished stems. FE analysis showed that the effects of cement creep and friction at the stem-cement interface on femoral strain were small compared with the effect of inserting a cemented stem.

There are few medium- and long-term data on the outcome of the use of proximal femoral structural allografts in revision hip arthroplasty. This is a study of a consecutive series of 40 proximal femoral allografts performed for failed total hip replacements using the same technique with a minimum follow-up of five years (mean 8.8 years; range 5 to 11.5 years). In all cases the stem was cemented into both the allograft and the host femur. The proximal femur of the host was resected in 37 cases.

There were four early revisions (10%), two for infection, one for nonunion of the allograft-host junction, and one for allograft resorption noted at the time of revision of a failed acetabular reconstruction. Junctional nonunion was seen in three patients (8%), two of whom were managed successfully by bone grafting, and bone grafting and plating respectively. Instability was observed in four (10%). Trochanteric nonunion was seen in 18 patients (46%) and trochanteric escape in ten of these (27%). The mean Harris hip score improved from 39 to 79. Severe resorption involving the full thickness of the allograft was seen in seven patients (17.5%). This progressed rapidly and silently, but has yet to cause failure of any of the reconstructions.

Profound resorption of the allograft may be related to a combination of factors, including a slow form of immune rejection, stress shielding and resorption due to mechanical disuse with solid cemented distal fixation, and the absence of any masking or protective effect which may be provided by the retention of the bivalved host bone as a vascularised onlay autograft. Although continued surveillance is warranted, the very good medium-term clinical results justify the continued use of structural allografts for failed total hip replacements with severe loss of proximal femoral bone.

We have previously described a simple and reproducible three-dimensional technique of CT for the measurement of the cover of the femoral head in acetabular dysplasia in adults. We now describe the application of this technique in ten patients with symptomatic dysplasia to assess the degree and direction of dysplasia and to measure the cover obtained at acetabular osteotomy.

The indices obtained gave a useful indication of the degree and direction of the dysplasia and confirmed which components had been used most efficiently to achieve cover. The information is easily presented in graphical form and gives a clearer indication of the cover obtained than the indices derived from plain radiographs.

We describe a patient with a Mason type-III fracture of the head of the radius associated with traumatic dislocation of the elbow. The radial head was intact throughout its circumference despite being completely detached from the shaft and devoid of any soft-tissue attachments. Severe comminution of the radial neck prevented reconstruction by internal fixation and precluded prosthetic replacement of the head. The head was fixed to the shaft with a tricortical iliac-crest bone graft which replaced the neck. Two years later, the patient had a stable elbow with flexion from 10° to 130°. Radiologically, the head of the radius appeared to be viable and the bone graft had incorporated.

Dental procedures may lead to a transient bacteraemia lasting for up to 30 minutes. Of the numerous cases of total hip arthroplasty (THA) reported which have been infected from haematogenous sources, dental procedures have been involved only infrequently. We reviewed the records of 2973 patients after THA. Of the late infections identified in 52 patients, three (6%) were strongly associated with a dental procedure. Infection was diagnosed by culture from the affected joint; Streptococcus viridans was identified in two cases and Peptostreptococcus in one. One patient had diabetes mellitus and another rheumatoid arthritis, both conditions predisposing to infection. The dental operations all lasted for more than 45 minutes and no patient received perioperative antibiotics.

Infection of a THA after dental procedures is more common than has been previously suspected. Patients with systemic disease, or who are undergoing extensive procedures, should be considered for prophylactic antibiotic treatment.

We examined macroscopically and microscopically 55 cadaver rotator-cuff tendons attached to their humeral heads to determine the distance between the edge of the articular cartilage and the tendon insertion of the supraspinatus (the width of the sulcus) and the score of regressive changes at the sulcus. In 33 specimens we measured the tensile strength. The width of the sulcus was correlated with the score of regressive changes and with the ultimate tensile strength of the supraspinatus tendon.

The width of the sulcus correlated positively with the score of regressive changes (r = 0.66, p < 0.0001), but there was a negative correlation between the latter and the ultimate tensile strength (r = −0.81, p = 0.001) and between the width of the sulcus and the ultimate tensile strength (r = −0.74, p = 0.004).

We believe that the width of the sulcus is a simple and useful clinical indicator of the integrity and the tensile strength of the supraspinatus tendon.

We have reviewed the results of 30 operations performed on 23 patients with Ficat stage-III or stage-IV osteonecrosis of the femoral head in which autogenous cortical and cancellous bone grafting had been performed through a so-called trapdoor made in the femoral head.

At a mean of 56 months (30 to 60) after operation 20 of 24 stage-III hips (83%) had a good or excellent result as determined by the Harris hip-scoring system. Two of six stage-IV hips (33%) had good or excellent results. Eighteen of 21 hips (86%) with a combined necrotic angle of 200° had good or excellent clinical results compared with only four of nine hips (44%) with a combined necrotic angle of more than 200°. Six of the eight hips which had fair or poor results were in patients who had received corticosteroids; five of these six hips had lesions with a combined necrotic angle of greater than 200° or were in a late stage (stage IV). There were no perioperative complications.

Our results suggest that the trapdoor procedure with autogenous cancellous and cortical bone grafting can be successful in Ficat and Arlet stage-III osteonecrosis of the hip in patients with small- to medium-sized lesions.

Limb salvage after loss of bone and soft tissue may require many operations to obtain soft-tissue cover and bony continuity. We describe a fibula-flexor hallucis longus osteomuscular flap which can provide both soft tissue and bone in a single stage. The flap is based on the peroneal vessels and is covered by a split-thickness skin graft.

We report the results in five patients with an average bone defect of 8.3 cm and soft-tissue and skin loss. All regained a normal gait on the donor side; four had clinical and radiological union with excellent soft-tissue cover, but one required later amputation due to diffuse coagulopathy.

The flap provides free vascularised bone with muscle cover. It has a dependable, long pedicle with minimal morbidity at the donor site, and allows monitoring of the vascularity of the fibular graft.

Posterior fixation of intervertebral discs is used to treat, and occasionally diagnose, discogenic pain since it is thought that it will reduce the internal loading of the discs in vitro. We measured the internal loading of ten intervertebral discs using stress profilometry under simulated physiological loads and then after posterior fixation. Partial discectomies were performed to simulate advanced disc degeneration and the sequence repeated.

Posterior fixation had very little effect on the magnitude of the loads acting on the disc and none when disc degeneration was simulated. It did, however, reduce bulging of the anterior annulus under combined bending and compression (p < 0.03). Recent experiments in vivo have shown that discogenic pain is associated with abnormal bulging of the annulus which suggests that the clinical benefit of fixation may be due to this.

We investigated the distribution of compressive ‘stress’ within cadaver intervertebral discs, using a pressure transducer mounted in a 1.3 mm diameter needle. The needle was pulled along the midsagittal diameter of a lumbar disc with the face of the transducer either vertical or horizontal while the disc was subjected to a constant compressive force. The resulting ‘stress profiles’ were analysed in order to characterise the distribution of vertical and horizontal compressive stress within each disc. A total of 87 discs from subjects aged between 16 and 87 years was examined.

Our results showed that age-related degenerative changes reduced the diameter of the central hydrostatic region of each disc (the ‘functional nucleus’) by approximately 50%, and the pressure within this region fell by 30%. The width of the functional annulus increased by 80% and the height of compressive ‘stress peaks’ within it by 160%. The effects of age and degeneration were greater at L4/L5 than at L2/L3, and the posterior annulus was affected more than the anterior. Age and degeneration were themselves closely related, but the stage of degeneration had the greater effect on stress distributions.

We suggest that structural changes within the annulus and endplate lead to a transfer of load from the nucleus to the posterior annulus. High ‘stress’ concentrations within the annulus may cause pain, and lead to further disruption.

We reviewed 11 patients (17 ankles) who had had core decompression for symptomatic avascular necrosis of the talus before collapse. The Mazur grading system was used to assess function preoperatively and at final follow-up, and radiographs were graded according to the Ficat and Arlet (1980) classification modified for the ankle.

At a mean follow-up of seven years (2 to 14) 14 ankles (82%) had an excellent or good outcome (Mazur scores > 80 points; pain scores > 40 points (41 to 50)). The other three ankles required tibiotalar fusion at a mean of 13 months (5 to 20) after core decompression.

We conclude that core decompression is a viable method of treatment for symptomatic avascular necrosis of the talus before collapse.

A case is reported in which fractures of the radius and ulna were fixed with Vitallium plates and screws. Seven years later a painful swelling appeared over the extensor aspect of the forearm. After eight years sarcoma was suspected and a pale tumour infiltrating muscle was found at operation. However, the histology excluded neoplasia and showed massive fibrosis and patchy necrosis of muscle, with chronic inflammatory changes peripherally. After the removal of the metal the swelling disappeared. A sinus down to the ulna followed operation and was not cured two years later. At this stage standard patch testing showed skin sensitivity to cobalt. Metal sensitivity is proposed as the cause of this extraordinary reaction in muscle.

1. Two cases of haemangioma of the patella are reported.

2. In one case pain alone brought the patient for treatment; in the other, a pathological fracture was the first symptom.

3. In neither case was a firm diagnosis made before excision and histological examination of the patella.

4. In each case a good result followed removal of the patella: this is probably the best method of treatment.

5. The literature relating to haemangioma of bone and to tumours of the patella is briefly reviewed.

Two cases of ganglion arising in the alar folds of the infrapatellar fat pad are reported. Both patients had symptoms of internal derangement of the knee, sufficient to justify operation.

1. A radiological study of the acromio-humcral interval in sixty normal shoulders and in fifty-nine shoulders with known tears of the rotator cuff is reported.

2. The normal acromio-humeral interval was found to be seven to fourteen millimetres, a range that is consistent with previous observations.

3. Narrowing of this interval is a frequent concomitant of a tear of the rotator cuff.

4. An interval of five millimetres or less should be considered compatible with a tear of the rotator cuff until proven otherwise.

5. An explanation of the pathomechanics of the observation has been proposed.

1. A total of 120 Moore's arthroplasties in 111 patients were reviewed one to nine years after operation.

2. There was striking reduction in the severity of pain in 105 out of the 120 hips reviewed. Range of movement was improved in most patients but the degree of independence was improved less often. The reasons for this are discussed.

3. We draw the following conclusions regarding the place of Moore's arthroplasty. Firstly, it was a natural step in the evolution towards total hip replacement, an operation which promises to give more complete relief of symptoms and which seems likely to replace Moore's arthroplasty as the treatment of choice in osteoarthritis of the hip in the elderly. Secondly, Moore's arthroplasty is still a rational procedure for the treatment of degeneration if the acetabulum is not involved—for instance, in idiopathic avascular necrosis of the femoral head. Thirdly, it is certainly a valuable operation for some cases of recent fracture of the femoral neck. Avascular necrosis of the femoral head after trifin nailing can be satisfactorily treated by Moore's arthroplasty, particularly in the early stages before the acetabulum becomes involved. Finally, Moore's arthroplasty gave many fairly elderly patients considerable relief of pain at a time when nothing better was available. Much of the relief afforded has proved to be lasting, but deterioration sometimes occurred with time. In the few patients whose deterioration amounted to failure a definite cause for the failure was found. In the majority the deterioration was slight, and it seems likely that the operation will last most of these elderly patients for the rest of their lives.

1. A case of total dislocation of the cuboid bone without fracture is described. This is an uncommon injury and to our knowledge has not previously been reported.

2. Its rarity is explained in the light of the structural anatomy and function of the foot.

3. A mechanism of injury is postulated and a method of reduction and fixation described.

I have tried to describe the functional attainments of amputees using conventional prostheses. I have outlined the work we have been doing on pneumatic arms for infants and children. I have discussed some of the practical problems in applying pneumatic and myo-electric systems to adults. The inescapable conclusion that one must reach is that two basic clinical requirements must be met before really significant advance is made in this field. Firstly, we must find a method of providing sensory information from the prosthesis. Secondly, we must find a way of utilising more control sites. So far we have only been able to make use of direct movements or myo-electric signals. In the high level bilateral subjects more controls are required than appear to be available. Capener has suggested, in more than one discussion that I can recall, the possibility of using the voice and I have no doubt that a subject could be trained to reserve certain frequencies for prosthetic controls. It may be that we will have to think along some such lines as this.

1. Congenital defects of the extremities are described. Although the detailed anatomy is infinitely variable, a broad classification in relation to prosthetic management has been suggested.

2. Most patients with these deformities can be fitted with a prosthesis without major surgical intervention. With this they will have at least as good function as they would have after amputation. A plea is made for a conservative attitude in this respect. It is suggested that recourse to amputation should be confined to cases in which prosthetic equipment falls short of functional and cosmetic requirements, and that, when possible, it should be deferred until the child is old enough to share in the decision.

3. The prostheses applicable to the various types of deformity are briefly described.

4. The application of similar techniques to cases of acquired shortening is mentioned.

5. The incorporation of certain features of artificial arms in flail arm splints is discussed.

1. A case is described of fatigue fractures occurring in the lowest thirds of the right tibia and fibula simultaneously.

2. The fibular fracture was a runner's fracture.

3. The tibial fracture was ascribed to the application of a below-knee walking plaster to treat the fibular lesion.

4. Both fractures were slow in uniting.

5. The fractures occurred in a rapidly growing youth but no clinical evidence of an endocrine dysfunction was found.